Professor Cryan's Research Profiled in Nature
Nature News, Gut–brain link grabs neuroscientists. Idea that intestinal bacteria affect mental health gains ground.
The immune system almost certainly plays a part, Mazmanian says, as does the vagus nerve, which connects the brain to the digestive tract. Bacterial waste products can also influence the brain — for example, at least two types of intestinal bacterium produce the neurotransmitter γ-aminobutyric acid (GABA)2.
The microbiome is likely to have its greatest impact on the brain early in life, says pharmacologist John Cryan at University College Cork in Ireland. In a study to be presented at the neuroscience meeting, his group found that mice born by caesarean section, which hosted different microbes from mice born vaginally, were significantly more anxious and had symptoms of depression. The animals’ inability to pick up their mothers’ vaginal microbes during birth — the first bacteria that they would normally encounter — may cause lifelong changes in mental health, he says.